The three projects in this PO1 will continue to share a core set of facilities which has two favorable results. First, this sharing is highly effective in cost and management time. Second, students and fellows interact during use of this common equipment promoting collaboration and cross fertilization. All Project Leaders and PI in this Program have offices and laboratories within 100 feet of one another. Some of the facilities supported in part by the PO1 core include a shared darkroom, centrifuges and microscopes. In these cases, maintenance contracts and supplies are supported. A Core facility for shRNA-vector libraries technician for use of short RNA hairpin vectors will be shared by all three projects. This technician will have laboratory space on the same floor as the three projects. All of the projects propose experiments where either large or small libraries of retro viral shRNA vectors will be used. These libraries are currently available from three sources, the Broad Institute RNA/Consortium, a library developed at Cold Spring Harbor by Dr. Greg Hannon, and a library developed by Dr. Ren6 Bernards of the Netherlands Cancer Institute. The RNAi Consortium based at MIT's Broad Institute is led by Professor William Hahn, a consultant to the Core. The Consortium has developed approximately 150,000 shRNA-lentivirus vectors which are targeted to silence approximately 30,000 genes orisoforms of genes. There will be other such libraries developed in the future. The Core will acquire, maintain and develop methods for optimalscreens with these RNAi libraries. The technician will also interact with the Virus Production Core Facility in the Center for Cancer Research. This will be both cost effective and insure a high quality of experimentation. Many of the above viral stocks are arrayed in microtiter dishes and to fully implement their use, a robotic system must be used to automate their distribution.